Hello,
There is an inconsistency in this code:
/sound/soc/imx/imx-ssi.c: ssi->dma_params_tx.burstsize = 4;
/sound/soc/imx/imx-pcm-dma-mx2.c: ssi->dma_params_tx.burstsize = 6;
Datasheet:
This sets the field TFWM0 in register SFCSR (SSI_SFCSR_TFWM0): the
number of data words needed to set the empty flag (TFE0). Can be set
from 1 to 8; FIFO size is 8 words (of 24b). And this is also the DMA
burst size.
Which is best depends on the application (the higher the more efficient,
but the more risk for a FIFO underrun). I would take 4.
But I guess it should only be set at 1 place, and what is then the best
place?
Regards,
Jürgen
details:
/sound/soc/imx/imx-ssi.c: ssi->dma_params_tx.burstsize = 4;
Set in commit
commit 0a93421b6adf8ba127b3eafc4c16e3a14017e2ae
Author: Javier Martin <javier.martin at vista-silicon.com>
Date: Tue Mar 1 15:02:06 2011 +0100
ASoC: Fix burstsize and DSP_B format problems in imx-ssi.
When choosing IMX_DMA flag, burtsizes are set to its default
value (0) which leads to driver malfunction. Change them to 4.
DSP_B interface needs additional flag to match DSP_B formats
as described in several codecs as wm8741 and aic3205.
Signed-off-by: Javier Martin <javier.martin at vista-silicon.com>
Acked-by: Liam Girdwood <lrg at slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie at opensource.wolfsonmicro.com>
Index in diff:
diff --git a/sound/soc/imx/imx-ssi.c b/sound/soc/imx/imx-ssi.c
index 30894ea..bc92ec6 100644
/sound/soc/imx/imx-pcm-dma-mx2.c: ssi->dma_params_tx.burstsize = 6;
Set in commit
commit 2c4cf17a52f04fbe929977252d5b8ab81d2c6e9b
Author: Wolfram Sang <w.sang at pengutronix.de>
Date: Fri Mar 25 16:51:44 2011 +0100
ASoC: imx: set watermarks for mx2-dma
They got accidently removed by f0fba2a (ASoC: multi-component - ASoC
Multi-Component Support). Reintroduce them and get rid of the
superfluous defines because the fiq-driver has its own hardcoded
values.
Signed-off-by: Wolfram Sang <w.sang at pengutronix.de>
Acked-by: Liam Girdwood <lrg at ti.com>
Signed-off-by: Mark Brown <broonie at opensource.wolfsonmicro.com>
Cc: stable at kernel.org
Index in diff:
diff --git a/sound/soc/imx/imx-pcm-dma-mx2.c
b/sound/soc/imx/imx-pcm-dma-mx2.c
index 671ef8d..b2ed764 100644
--
Jürgen Lambrecht
R&D Associate
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